Abstract
Quinoxaline derivatives formed from malto-oligosaccharides (maltose, maltotriose, maltotetraose, maltopentaose, and maltohexaose) and o-phenylenediamine (OPD) under alkaline and heated conditions were studied for the measurement of the degree of polymerization by HPLC analysis. 2′S)-2-(2′, 3′-Dihydroxypropyl)-3-hydroxymethyl- quinoxaline (M-1) from reducing end residue and six quinoxalines from non-reducing end residue were obtained by the alkaline OPD method. The ratio of the peak area for M-1 to 2-methylquinoxaline (G-VI) was proportional to the degree of polymerization of the malto-oligosaccharides tested. From 62-O-α-maltosyl maltotriose, which has both 1, 4- and 1, 6-linkages, a quinoxaline having a sugar moiety in its branch was separated with other smaller quinoxalines. From this chromatogram, some proportional relationships between the ratio of this quinoxaline to G-VI and the average number of branched chain were estimated.
